1. Field of the Invention
This invention relates to improvements in and relating to slide fasteners of a separable construction, and more particularly to such a slide fastener which is equipped with two separate sliders to permit the fastener to be opened and closed in opposite directions.
2. Prior Art
There have been proposed numerous slide fasteners having a separator constituted by a pin member and a socket member releasably interengageable therewith. Pin members according to one known method were formed either by injecting a thermoplastic material into the region of a fastener tape edge where the fastener elements had been previously removed, or by attaching a preformed pin member to such element-free tape edge. This method was complicated and time-consuming, involving the removal of fastener elements, or attaching separate pin members to the tape edge. Another known method of forming a pin member was to fuse a theremoplastic film integrally with a length of fastener elements on a pair of stringers which had been coupled together. Neither of these methods is satisfactory in respect of the cost involved in using extra material, particularly expensive plastic material. A further drawback was encountered with the prior art separable fasteners in that terminal ones of fastener elements were often loosened up or shifted out of position with the results that the fastener elements were prone to undergo "mis-meshing" or consequent "rupture" or separation of meshed element chains during use of the fastener.
There was another drawback of the conventional form of separable slide fastener in that the slider was required to be mounted on one of the two stringers from the upper end thereof remote from the lower end to which the pin member having a slider-locking part is affixed. This slider mounting operation, usually manual, was tedious and laborous particularly where the fastener is relatively long as in the case of reversibly separable slide fasteners having two oppositely oriented sliders or "loop" fasteners having a single stringer. With sliders mounted on the stringers prior to attachment of pin members, then the sliders would often present themselves to be an obstacle to the mounting of pin members or to the sewing of stringers onto a garment fabric.